Round Goby &
Zebra Mussels on
a Native Mussel
Zebra Mussels Encrusted
on Marine Equipment
Water Hyacinth Dominating an Aquatic System
Purple Loosestrife Dominating an Aquatic System
Giant Salvinia Dominating a Canal System in AZ
Boatload of Asian Carp
Aquatic Weeds on
Aquatic Nuisance Species Impacts
Number of nonindigenous species in selected ecosystems:
- Oil spills can be cleaned up, but biological spills are forever!
- Annually, 21 billion gallons of ballast water--2.4 million gallons per hour/40,000 gallons per minute--containing thousands of nonindigenous species are discharged into U.S. waters.
Rate of Introductions of NIS
- San Francisco Bay/Inland Delta, CA--234 species (plus up to 123 others).
- Great Lakes--139 species
- Hudson River, NY--154 species
- Coos Bay, OR--67+ species
- Florida inland waters--154+ species
- Chesapeake Bay--120+ species
- Hawaii--4,465 species
- U.S. (OTA 1993) -- 4,500+
- Proportion causing serious harm -- 15%
- OTA Report (1993) concluded the rate of harmful introductions appeared stable.
- 1980-1993 (OTA 1993) -- 200
- Number expected to be harmful -- 59
- San Francisco Bay/Inland Delta (see chart)
- 1850-1995 -- average of one every 36 weeks
- 1970-1995 -- average of one every 24 weeks
- 1985-1995 -- average of one every 12 weeks
Nonindigenous species are major, but generally unrecognized, stressor of ecosystems.
- 42% of listed species significantly impacted by NIS.
- Major cause of decline of species and significant impediment to recovery.
Mitten Crabs in San Francisco Bay/Inland Delta, CA
- Introduced in 1986 into Lake St. Clair near Detroit in ballast water discharges; now infest
waters from Vermont to Oklahoma and Ontario to the Gulf of Mexico.
- Great Lakes water users spend $30 million annually to monitor and control zebra mussels.
- Causing massive changes in the Great Lakes ecosystem, including elimination of native mussels and toxic algae blooms
- Substantial concern about impacts on fishery resources and fishery restoration efforts.
Brown Tree Snake
- Have spread rapidly since found in South San Francisco Bay in 1992; now present throughout the estuary.
- Burrowing threatens banks and levees/dikes protecting agriculture and urban areas.
- Damages rice fields by consuming rice shoots and burrowing.
- Compete with commercially important species like crawfish.
- Damage fishing nets and catch.
- Nuisance to recreational fishermen (e.g., steal bait).
- Also have been found in Louisiana and Lake Erie.
- Introduced to Guam during WWII in returning military equipment
- Currently, Guam is heavily infested; may be established on Saipan; poised to invade Hawaii, other Pacific Islands, U.S. mainland.
- Caused more than 1,200 electric power outages since 1980, some island-wide lasting several days; an average of one outage every five days since 1980.
- Venomous bites are a public health concern; life threatening to infants.
- Invade homes, farms; kill chickens, other domesticated animals.
- Caused extirpation of nine native birds on Guam; threatening other species.
Lake Trout in Yellowstone Lake, WY
- Introduced in early 19th Century in solid ballast and as an ornamental; presently occurs in 42 States.
- Annual management costs and lost forage value: $45 million.
- Displaces native wetland plants with monotypic stands with little value to waterfowl, other wildlife.
- Introduced in 1970s or early 1980s.
- Population likely to expand and cause precipitous decline in Yellowstone cutthroat trout population to 10 to 20 percent of current levels.
- Threatens world-famous fishery in Yellowstone Lake and its tributaries; any lake trout fishery will be far less significant socially and economically.
- Native cutthroat trout are food source for 42 mammals and birds in the ecosystem, including endangered grizzly bear and bald eagle. Many species abundance in the ecosystem depends on the availability of Yellowstone cutthroat trout--lake trout will not fill this ecological niche.
- Introduced into Duluth, MN/Superior, WI, Harbor in early-1980s; has spread on its own 150 miles eastward along the South Shore of Lake Superior and by ballast water to Lake Huron.
- Caused precipitous decline of nine native fish species in Duluth/Superior Harbor; ruffe are now more abundant than other fish species combined.
- Decline in value of fisheries in U.S. Great Lakes due to ruffe infestation expected to be $119 million.
- Massive invasion of Great Lakes after Welland Canal opened in 1929.
- Major factor in collapse of lake trout populations and fisheries in 1940s and 1950s.
- Populations reduced 90% by chemical control that presently costs the U.S. and Canada more than $12 million annually. Control efforts have allowed successful efforts to restore lake trout.
- Sea lamprey populations have been increasing in recent years which threaten fishery restoration.
Cost U.S. economy
- 100 million acres infested, infestation expanding at 10 million acres per year.
- Rate of infestation of Federal lands by weeds: 4,600 acres per day.
- Annual expenditures by six Federal agencies related to weeds: $11 million
- FWS lands outside Alaska infested: 1.4 million acres.
Impediment to Ecosystem Restoration
- Billions annually.
- 79 animal and plant species, 1906 to 1991: $79 billion.
- 15 recent introductions could cost the U.S. $134 billion by 2050.
- Sea lamprey control costs (U.S. and Canada): >$12 million/year
- Purple loosestrife management cost and lost forage value: $45 million/year
- Expenditures by 6 federal agencies related to weeds: $11 million/year
- Present worth of decreased economic value of sport and commercial fisheries in the U.S. Great Lakes attributable to a fully developed ruffe population: $119 million.
- Annual zebra mussel control/adaptation costs incurred by major raw water users in the Great Lakes : $30 million/year
- Lost productivity of rangelands due to weeds (annual): $3.6 to $4.5 billion.
- Lost productivity of 64 crops due to weeds, 1984: $7.8 billion.
- In heavily invaded systems, historic conditions are no longer a valid indicator/guide of what type and level of restoration can be accomplished. May have to develop entirely new goals and objectives requiring delays for further study and additional investments before can ensure effective restoration.
- Florida Everglades
- Melaleuca tree lowers water levels.
- Melaleuca and Brazilian pepper tree crowd out diverse native vegetation and replace it with sterile, single species stands.
- Mayan chiclid displaces native fish, but increases food supply for endangered wood storks.
- San Francisco Bay/Inland Delta
- Food web and other components of ecosystem have been changed by many invaders.
- Salmon restoration goals and objectives based on population and other data for the 1970s and earlier may no longer be valid.